CMOS-based mm-wave transceivers have received great attention in recent years. The promise of integrating mm-wave transceivers with commercial electronics opens up opportunities in wireless communication, automotive, medical, and security industries, to name a few. Prior research demonstrated successful functionality of integrated mm-wave transceivers. Unfortunately, due to the lack of a locking mechanism, these transmitters were limited to single-chip operation without reaping the potential benefits of a coherent multi-chip system with widely-spaced elements. Challenges for a single-chip mm-wave system include the limited amount of power generated and the low pattern directivity due to the small size of the on-chip antennas.
In order to achieve coherency in a multi-chip system, transmitters have employ locking through a wired connection, either in the form of a phase-locked loop for continuous-wave systems, or a digital square-wave trigger signal for pulsed systems. Unfortunately, the wired connections limit the scalability of the array and are not suitable for building synchronous arrays via mobile objects such as satellites, UAVs, or airborne systems. A wireless locking architecture can resolve this issue. An optical signal generated by a free-space laser locks the on-chip oscillator was contemplated in other work. However, the narrow beamwidth of the laser limits the operation angle and requires high-precision alignment, making it unsuitable for low-cost, mobile applications. In contrast, mm-wave wireless locking exhibits wider operation angle. Other work has also demonstrated the possibility of generating a 1.875 GHz local clock signal using a 15 GHz wireless signal. However, the range of operation in such work was limited to a few centimeters, and no radiation or spatial combining was performed.
Systems and methods providing wireless synchronization of a mm-wave array with high frequency stability wireless injection locking are discussed herein. The proposed systems and methods enable rapid scaling of the size of an array by eliminating the need for wires to connect the injection source to the widely-spaced chips. In addition, the proposed methodology can be used to build an array on a non-planar substrate or on a mobile platform.